Replies

Success with the linear actuator. Once I measured the right combo of two possibilities of three wires, red and black or red and white, I get a reading that makes sense.

Last night when I used the red and black wires, it made no mathematical sense. 50% on voltage was about 20% extended on the actuator. Of course there’s no instructions that tell you which pair of wires to take readings from. They may have info or schematics for electrical engineers.

In either case I had a range of about a 6 volt reading through a potentiometer/resistor from a 12 volt input. In the case of reading between the red and white wires, 5 - 11 vdc with the half way point being 8 vdc because 5+3=8 and 11-3=8.

Extended the actuator half way and it read 8 vdc. Now I can figure out any position from there. Half of 6 is 3 and half of that is 1.5. If 8 vdc is 50%, take 1.5 away and 6.5 is 25%. Add 1.5 and 9.5 is 75%. Works for me.

I’m not getting into the math of 6 vdc = 100% of travel because 6 is a crappy number for that. Lots of .33333333 and .66666666 type numbers.

Knowing this

0% open (5.0vdc)
25% open (6.5vdc)
50% open (8.0vdc)
75% open (9.5vdc)
100% open (11vdc)

Close enough and observation will do from there.

Knowing this
0% open (5.0vdc)
25% open (6.5vdc)
50% open (8.0vdc)
75% open (9.5vdc)
100% open (11vdc)

Close enough and observation will do from there.

I had that backwards. 11 vdc is actually retracted and 5 vdc is extended. Scaling that will make it 0% = open and 100% = closed. My brain will never deal with that.

Now I have to figure out how to reverse the numbers. From what I gather, it's called an Inverse Function in algebra but I never could get my head wrapped around algebra. Video preview screens don't look promising.

Just spent 5 minutes redesigning the mechanical aspect of the tunnel sides so that when the actuators retract, it opens the sides. Now it will be 0% = closed and 100% = open; as soon as I rewatch a video tutorial on linear equations aka scaling. Gable vents and my seed room will be easy as they're small. Just add a 4" arm sticking out 90 degrees at the top and pull it down to open instead of pushing out on the bottom. It will actually work out better because the 4" actuator is 14" long and would stick out into the room that far. Had no idea how I was going to mount it like that. Now I can just mount it vertically against the wall. For the gable vents, I can mount the base end to the bottom of the vent frame.

I'm already using an arm on the sides so the redesign was simply mounting the stationary end of the actuator in the opposite direction to pull the arm instead of push. Way easier than algebra. Either way, it was going to need a counterweight like old house windows had as a helper. I'm going to set it up so I can open them by hand easily and then add the actuator.

If an actuator fails, I can pull the pins to detach it and open the side by hand. I can make an adjustable rod to use in it's place. One tube that slides inside another with holes for a pin to lock it in different positions. I fact, I think I'll do that to start so I can open/close manually until I can afford the motorization components. I already have the specs for the long actuators with distance between mounting pins when retracted/extended.